In the rail industry, rail vehicles are utilized to transport passengers and/or cargo from location to location on a track. Typically, a locomotive provides the motive power for a train. Locomotives often have one of two body styles, namely, a platform style (also referred to as a cowl unit style) or a carbody unit style. In the case of a platform-style locomotive, the locomotive has full-width enclosing bodywork. The bodywork is simply a casing or a tent-like structure and is not load bearing. Instead, all the strength of a platform-style locomotive is in the locomotive's platform structure/frame, beneath the floor. Locomotives having a platform body style are often quite heavy, as large beams and other substantial structural members are needed to support the full weight of the locomotive components such as the engine, fuel, alternator, cooling system, etc.
In contrast to a platform design, a carbody unit, or simply carbody, derives its structural strength from a bridge-truss framework in the sides and roof, which cover the full width of the locomotive. When constructing the carbody, residual stresses build up due to the manufacturing process and/or shape of the framework. Accordingly, in order to safely support the full weight of the locomotive components, the carbody framework must actually be over-engineered to account for residual stresses in the carbody. This over-engineering may take the form of thicker frame members, resulting in added weight.
In certain instances, however, weight of the locomotive is a primary concern. For instance, rail safety organizations may have maximum weight requirements. In particular, the weight of a locomotive may be a primary concern when traveling over certain bridges or other areas of track. Accordingly, it may be desirable to reduce the weight of a locomotive by eliminating residual stresses associated with the manufacture of the locomotive, thus eliminating the need to over-engineer the structural members of the carbody to compensate for residual stresses therein.